A wildfire burned 85 acres of ranch land and eucalyptus trees Monday north of Novato. The fire broke out around 4:30 p.m. east of Highway 101 and just north of the Sonoma County line. “There was a clear, distinct column of smoke,” said Novato fire Battalion Chief Eric Nickel. The incident forced emergency crews to close one lane of northbound 101 for fire vehicles, causing rush-hour traffic to back up into Novato. The lane was reopened at 8:11 p.m., the California Highway Patrol said. The flames spread within 100 yards of a residence but caused no injuries. The cause is being investigated.